Typical truck like motor vehicle arrangements have two spaced apart supporting side rails. Supported between the side rails is an engine block forward of a transmission. The engine block is fixably connected with a bell housing of the transmission. To selectively torsionally connect a crankshaft of the engine with an input shaft of the transmission there is provided a clutch assembly 10.
An exemplary motor vehicle clutch assembly 10 is shown in FIG. 1. The clutch assembly 10 is disposed between the transmission input shaft 12 and an engine crank shaft (not shown). The clutch assembly 10 has an axis of rotation 13 about which the clutch assembly 10 and input shaft 12 rotate. A flywheel 14 is configured to be rigidly fixed to the engine crank shaft. A cover 16 is rigidly mounted to the flywheel 14. A pressure plate 18 is rotatably fixed to the cover 16 by means, such as one or more flexible straps 19, which allow the pressure plate 18 to move axially relative to the cover 16. A driven disc 20 is axially disposed between pressure plate 18 and flywheel 14.
A retainer 21, encircling a sleeve 36 is engaged by a plurality of apply springs 24 and levers 26. Levers 26 pivotably contact an adjusting mechanism 28 and engage the pressure plate 18. The apply springs 24 bias the levers 26 against the pressure plate 18.
To release the clutch assembly 10, thereby torsionally disconnecting the transmission from the engine there is provided a release bearing assembly 34. The release bearing assembly 34 is connected to the retainer 21 by the retainer sleeve 36. A snap ring keeps the release bearing assembly 34 on the sleeve 36. The release bearing assembly 34 includes both a bearing housing 42 and a roller bearing 40 with inner and outer races with the outer race non-rotatively placed therein. The release bearing assembly is typically lubricated with grease via a fitting on its housing.
To cause the release bearing assembly 34 to release the clutch 10 there is provided a release fork (not shown in FIG. 1). Prior to 1990, most release forks were manually operated by a linkage connected with a clutch pedal inside a vehicle cab. Typically the release fork had a stem oriented almost horizontally. According a lube tube (commonly refereed to as a hose) was typically connected to the release bearing housing in the 6 o'clock position. The lube tube 6 o'clock position was the predominant design on large commercial truck vehicles.
To make operation of the vehicle clutch easier for the vehicle operator, a new hydraulically powered release fork design has been developed (shown in FIG. 2) commonly referred to as a catapult style release fork. Due to other design considerations, most catapult style release fork designs 107 with preloaded hydraulic linkages commonly used on commercial vehicles move the stem 120 of the fork 108 to the 6 o'clock or near 6 o'clock position. The catapult style clutch release fork eliminates the possibility of routing a lubrication path to the clutch release bearing 34 in the traditional manner that is well known throughout the commercial vehicle industry. As mentioned previously, in the manual linkage type release fork design (commonplace until approximately the late 1990's), a clutch release bearing lubrication path is simply routed using a lubrication or grease hose 77 fastened to a clutch release bearing grease port located on the bearing housing at the 6 o'clock position. The 6 o'clock release bearing grease port configuration allows the grease hose 77 to drop downward from the clutch release bearing housing and hang through the bottom of the transmission bell housing and provides an easy accessible grease point for the clutch release bearing (It should be noted that due to the lack of access from above, lubrication maintenance of the release bearing must occur from underneath the bell housing of the transmission). The geometry of the catapult style clutch release fork used with preloaded hydraulic linkages forces the running position of the clutch release bearing to be rotated 180 degrees which places the traditional grease port (sometimes referred to as fitting) on the clutch release bearing to be located in the 12 o'clock or near 12 o'clock position. In this position, a standard grease hose cannot be utilized to create a lubrication path to the clutch release bearing. The current practice of using a non-traditional grease hose fastened to the clutch release bearing and exiting the transmission bell housing at a location other than the 6 o'clock position creates problems with lubricating the clutch release bearing and also increases the complexity of lubrication path routing for original equipment manufacturers (OEM) assembly personnel for new truck builds. With the grease point of the clutch release bearing located in the non-traditional position, the risk of truck service personnel missing a clutch service interval increases. This can lead to a premature clutch failure due to lack of lubrication to the release bearing. The non-traditional grease hose used with preloaded hydraulic linkage systems requires additional labor to fasten a grease hose 122 to the bearing itself and also the side of the transmission bell housing a bulk head type fitting 123 since the grease hose is not able to hang down in a vertical position. Another hose 125 is required to hang downward terminating in a lateral non-traditional position. Another problem is that the hose 122 from the release bearing housing to the bulk head receives great stress due the axial movement of the release bearing. Still another problem is that failure of the hose 122 or fitting from the bearing housing 42 to the bulk head is not observable by a maintenance worker working from underneath the transmission bell housing.